Floor cleaning apparatus

ABSTRACT

Floor cleaning apparatus ( 1 ) comprising: a) a front portion ( 16 ) and a rear portion ( 17 ); the rear portion ( 17 ) comprising two lateral rear wheels ( 3 ); b) a chassis ( 2 ) and c) a cleaning unit ( 4 ) attached to the chassis ( 2 ), wherein the cleaning unit ( 4 ) comprises at least one rotatable brush ( 20 ) which is arranged in the front portion ( 16 ) of the cleaning apparatus ( 1 ) so as to be contactable with the floor ( 12 ) to be cleaned and a suction device ( 25 ) including a front suction unit ( 8 ) arranged in front of the at least one brush ( 20 ) and a rear suction unit ( 7 ) arranged rearward of the at least one brush ( 20 ), wherein the front suction unit ( 8 ) comprises a front suction channel ( 29 ) and a closing member ( 26 ) for closing the front suction channel ( 29 ).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a floor cleaning apparatus according to thepreamble of claim 1 and to a method for cleaning a floor using the sameaccording to the preamble of claim 27.

2. Description of the Related Art

An apparatus for cleaning a floor surface is known from U.S. Pat. No.5,901,410 WINDMEISSER. This known cleaning apparatus is suitable for wetcleaning and comprises a front suction unit in front of the brushingmeans and a rear suction unit behind the brushing means. Fresh cleaningliquid is supplied to the brushing means from a first tank in eithertravel direction. The front suction unit and the rear suction unit bothextend parallel to the brushing means and are both connected to a secondtank. The cleaning liquid is sucked up by the rear suction unit when thecleaning apparatus is moved in forward travel direction and sucked up bythe front suction unit when the cleaning apparatus is moved in abackward travel direction. A drawback of this known device is that bothsuction units are always active in either travel direction of thecleaning apparatus but only one of the front and rear suction units isused to suck up the cleaning liquid applied to the floor via thebrushing means.

BRIEF SUMMARY OF THE INVENTION

It is an object of the invention to provide a floor cleaning apparatuswhich has a front and a rear suction unit and which permits to eitherincrease the vacuum applied to a suction unit or to increase the suctionvolume flow rate without changing the vacuum turbine power.

The invention solves the posed problem with a floor cleaning apparatuscomprising the features of claim 1 as well as with a method for cleaninga floor using the same and comprising the features of claim 27.

The advantages of the floor cleaning apparatus according to theinvention are essentially to be seen in the facts that:

-   -   during a movement of the cleaning apparatus in the forward        travel direction the front suction channel is closed and the        entire suction performance of the vacuum turbine is concentrated        on the rear suction unit. Due to the closed front suction        channel the suction volume flow rate is reduced and thus an        increased vacuum in the rear suction channel can be achieved        when the cleaning apparatus is moved in forward travel        direction;    -   during a movement of the cleaning apparatus in the backward        travel direction the front suction unit opens so that the front        suction unit and the rear suction unit actively suck up cleaning        liquid resulting in a combined high suction volume flow rate;        and    -   a vacuum turbine can therefore be used which has a constant        suction power when either both suction units are simultaneously        active thus allowing a high suction volume flow rate or when the        rear suction unit is active only thus allowing a high vacuum.

In a special embodiment the closing member closes the front suctionchannel when the cleaning apparatus is moved in a forward traveldirection.

In another embodiment the closing member opens the front suction channelwhen the cleaning apparatus is moved in a backward travel direction. Dueto this configuration the front suction channel can be opened or closedby simply changing the travel direction of the cleaning apparatus.

In a further embodiment the rear suction unit comprises a rear suctionchannel which remains open during both movements of the cleaningapparatus in the forward and backward travel direction. Thisconfiguration permits the advantage that because the rear suctionchannel is open in either travel direction the suction volume flow rateof the cleaning unit can simply be increased by moving the cleaningapparatus in the backward travel direction.

In a further embodiment the front suction channel comprises a suctionopening which is open towards a floor to be cleaned over the entirelength of the front suction unit and the closing member closes thesuction opening of the front suction channel when the cleaning apparatusis moved in a forward travel direction and opens the suction openingwhen the cleaning apparatus is moved in a backward travel direction. Bythis means a simple configuration of the closing member is achievable.

In another embodiment the front suction channel comprises a suctionopening which is open towards a floor to be cleaned and the closingmember comprises a lip with a front section which frontally limits thesuction opening along its entire length and a rear section whichrearwardly limits the suction opening along its entire length. By thismeans the advantage can be achieved that the front section of the lipcan be used to close or open the suction opening of the front suctionchannel.

Preferably, the closing member is actuated by frictional forces actingon the front section of the lip due to a sliding movement of the same ona floor to be cleaned when the cleaning apparatus is moved in theforward travel direction of the cleaning apparatus or in the backwardtravel direction of the cleaning apparatus. The advantage of thisconfiguration can be seen therein that the closing member can beactuated without any auxiliary drive or device and must not beseparately actuated by the operator. Preferably, the lip is made of aresilient material permitting the advantage that the front section ofthe lip is biased into its initial configuration where the front suctionopening is opened.

In a further embodiment the front section of the lip has a verticalheight HF and the rear section of the lip has a vertical height HR andwherein HF is larger than HR so that the front section is bendableacross the suction opening. By this means the advantage can be achievedthat when the cleaning apparatus is moved in the forward traveldirection the front section of the lip is bent under the rear section sothat consequently the suction slot is closed and only minimal or nosuction is effected by the front suction unit. When the cleaningapparatus is moved in the backward travel direction the front section ofthe lip initially contacts the floor to be cleaned and is pushedoppositely to the backward travel direction, i.e. towards the front endof the cleaning apparatus so that the suction slot of the front suctionunit is opened and the front suction bar fulfills in this condition thefunction of a standard suction bar.

Preferably, the front section of the lip is bendable as far as a portionof the front section extends below the rear section so that the suctionopening of the front suction channel can be completely closed.

In a further embodiment the rear suction unit comprises a rear suctionchannel and both of the front suction channel and the rear suctionchannel are connected to a manifold so as to be in fluid connection witha single vacuum turbine. The advantage of this configuration is that thecleaning apparatus can be operated with a single vacuum turbine.Preferably, the cleaning unit comprises a first electric driving motorfor the vacuum turbine and at least a second electric driving motor forthe at least one brush.

In again a further embodiment the front suction unit and the rearsuction unit extend transverse to the forward and backward traveldirection of the cleaning apparatus. Preferably, when measuredorthogonal to a vertical middle plane of the cleaning apparatus thefront suction unit and the rear suction unit each have a length which isequal to or larger than a dimension of the at least one brush orthogonalto the vertical middle plane.

In another embodiment the cleaning apparatus further comprises a brushhousing and the rear suction unit is attached to the brush housing bymeans of a resilient connecting device allowing the rear suction unit tomove laterally with respect to the chassis against an elastic resistanceprovided by the resilient connecting device.

Preferably, the resilient connecting device comprises an elasticconnector which forms a pivot joint affixed to the brush housing bymeans of a fastener. Preferably, the pivot joint has an axis of rotationextending essentially vertically.

In another embodiment the rear suction unit comprises a curved suctionbar, preferably an essentially elliptically curved suction bar.

In a further embodiment the resilient connecting device comprises anelongated bracket having a first end affixed to the rear suction unitand a second end attached to the brush housing by means of an elasticconnector. Preferably, the elongated bracket is biased in a position ofrest by means of the elastic connector wherein when in the position ofrest the elongated bracket extends along a forward or backward traveldirection of the cleaning apparatus.

In a further embodiment the at least one brush is rotatable about arotational axis extending essentially vertically.

In another embodiment the cleaning apparatus further comprises ahandlebar which is suitable to move the cleaning apparatus on a floor tobe cleaned.

Preferably, the rear suction unit is arranged in front of the rearwheels. This configuration permits the advantage that when moving thecleaning apparatus in a forward travel direction the rear wheels moveoutside of the wet area of the floor to be cleaned.

In a further embodiment the cleaning apparatus further comprises a firsttank which is attached to the chassis and which is configured as areceptacle with its smallest dimension X extending vertically withrespect to the forward and backward travel direction of the cleaningapparatus. Preferably, the cleaning apparatus further comprises a secondtank which is arranged in the rear portion of the cleaning apparatus andwhich is configured as a receptacle having a smallest dimension Z in theforward or rearward travel direction of the cleaning apparatus.

In another embodiment the cleaning apparatus can further comprise anelongated member which extends from the rear end of the chassis, whereinthe second tank is attachable to the elongated member. Preferably, oneend of the elongated member is rotatably affixed to the chassis by meansof a hinge. This configuration permits the advantage that the elongatedmember with the second tank attached thereto can be backwardly rotatedabout the rotational axis of the hinge so as to permit to clean thefloor under a table.

A BRIEF DESCRIPTION OF THE DRAWINGS

A special embodiment of the invention will be described in the followingby way of example and with reference to the accompanying drawings inwhich:

FIG. 1 illustrates a side view of an embodiment of the floor cleaningapparatus according to the invention;

FIG. 2 illustrates an exploded perspective view of the front portion ofthe embodiment of the floor cleaning apparatus according to theinvention shown in FIG. 1;

FIG. 3 illustrates a sectional view of the brush housing along thevertical middle plane;

FIG. 4 illustrates a magnified sectional view of detail B in FIG. 3; and

FIG. 5 illustrates a side view of an embodiment of the floor cleaningapparatus according to the invention shown in FIG. 1 with the secondtank additionally illustrated in a vertical and backward tiltedposition.

DETAILED DESCRIPTION OF THE INVENTION

Although the invention is described in conjunction with a specificembodiment thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims.

All publications, patents and patent applications mentioned in thisspecification are herein incorporated in their entirety by referenceinto the specification, to the same extent as if each individualpublication, patent or patent application was specifically andindividually indicated to be incorporated herein by reference. Inaddition, citation or identification of any reference in thisapplication shall not be construed as an admission that such referenceis available as prior art to the present invention. To the extent thatsection headings are used, they should not be construed as necessarilylimiting. The terms “comprises”, “comprising”, “includes”, “including”,“having” and their conjugates mean “including but not limited to”. Thisterm encompasses the terms “consisting of” and “consisting essentiallyof”.

The terms “front”, “rear”, “forward” and “backward” are understood asbeing directed to a “forward travel direction” of the cleaningapparatus, i.e. a movement of the cleaning apparatus by manually pushingthe handlebar towards the front portion of the cleaning apparatus sothat the same moves on the floor to be cleaned with the front portionahead. The term “backward travel direction” is meant to be the oppositetravel direction by pulling the handlebar so that the cleaning apparatusmoves on the floor with the rear portion ahead. The wording “lateral” orin “a lateral direction” is understood as located beside or extending ina cross direction with respect to the forward and backward traveldirection. Furthermore, the terms “lower side of the chassis”, “upperside of the chassis”, “above”, “below”, “vertical” and “horizontal” arereferenced to the cleaning apparatus positioned on the floor to becleaned.

The term “chassis” is understood as being a framework which supportsand/or holds in position the various parts of the cleaning apparatus andto which the handlebar is affixed and the rear wheels are rotatablyattached.

As used herein, the singular form “a”, “an” and “the” include pluralreferences unless the context clearly dictates otherwise. For example,the term “a brush” or “at least one brush” may include a plurality ofbrushes.

Throughout this application, various embodiments of this invention maybe presented in a range format. It should be understood that thedescription in range format is merely for convenience and brevity andshould not be construed as an inflexible limitation on the scope of theinvention. Accordingly, the description of a range should be consideredto have specifically disclosed all the possible subranges as well asindividual numerical values within that range. For example, descriptionof a range such as from 1 to 6 should be considered to have specificallydisclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numberswithin that range, for example, 1, 2, 3, 4, 5, and 6. This appliesregardless of the breadth of the range.

Whenever a numerical range is indicated herein, it is meant to includeany cited numeral (fractional or integral) within the indicated range.The phrases “ranging/ranges between” a first indicate number and asecond indicate number and “ranging/ranges from” a first indicate number“to” a second indicate number are used herein interchangeably and aremeant to include the first and second indicated numbers and all thefractional and integral numerals therebetween.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination or as suitable in any other describedembodiment of the invention. Certain features described in the contextof various embodiments are not to be considered essential features ofthose embodiments, unless the embodiment is inoperative without thoseelements. As used herein the term “method” refers to manners, means,techniques and procedures for accomplishing a given task including, butnot limited to, those manners, means, techniques and procedures eitherknown to, or readily developed from known manners, means, techniques andprocedures by practitioners of mechanical engineering.

The word “exemplary” is used herein to mean “serving as an example,instance or illustration”. Any embodiment described as “exemplary” isnot necessarily to be construed as preferred or advantageous over otherembodiments and/or to exclude the incorporation of features from otherembodiments.

The word “optionally” is used herein to mean “is provided in someembodiments and not provided in other embodiments”. Any particularembodiment of the invention may include a plurality of “optional”features unless such features conflict.

FIGS. 1 to 4 illustrate an embodiment of the cleaning apparatus 1 forwet cleaning of a floor 12. The cleaning apparatus 1 essentiallycomprises a front portion 16, a rear portion 17 with two lateral rearwheels 3, a chassis 2 and a cleaning unit 4 attached to the chassis 2.Exemplarily, the cleaning apparatus 1 can be provided with a handlebar 6which is suitable to move the cleaning apparatus 1 on a floor 12 to becleaned. Alternatively, the cleaning apparatus 1 can be driven by amotor and controlled by the operator by means of control means attachedto the cleaning apparatus 1 or can be controlled by a remote control.The handlebar 6 can be attached to the chassis 2 by means of anessentially vertically extending elongated member 9, e.g. a post so thatthe handlebar 6 permits to move the cleaning apparatus 1 manually in aforward and a backward travel direction. In various embodiments of thecleaning apparatus 1 according to the invention the cleaning unit 4 cancomprise one or more brushes 20. Exemplarily, but not limiting, theembodiment of the cleaning apparatus 1 illustrated in FIGS. 1 to 5 isprovided with a cleaning unit 4 comprising two brushes 20. The twobrushes 20 are rotatably attached to a brush housing 22. The brushes 20are rotatable about a rotational axis 21 each. The brushes 20 can forexample, but not limited to, be arranged with their rotational axes 21extending vertically on opposite sides of the vertical middle plane 18and essentially vertically to the forward and backward travel directionof the cleaning apparatus. Alternatively, the one or more brushes 20 canbe arranged with their rotational axes 21 extending horizontally in alateral direction of the cleaning apparatus 1.

Further, the cleaning unit 4 can comprise a first tank 15, a second tank13, preferably two rotatable brushes 20 and a suction device 25permitting to suck up the dirty cleaning liquid. The first tank 15 isused for fresh water supply while the second tank 13 is used as arecovery water tank into which the dirty cleaning water sucked up fromthe floor 12 can be delivered by means of the suction device 25 via theflexible tube 33. Furthermore, the cleaning unit 4 can comprise a firstelectric driving motor (not shown) for driving the vacuum turbine 5 anda second and third electric driving motor (not shown) each for drivingone of the two brushes 20. The cleaning apparatus 1 can be provided witha battery 35, preferably a lithium-ion battery to supply the electricdriving motors with electric energy. The two brushes 20 can rotate withopposite senses of rotation.

Preferably, the first tank 15 is configured as a fresh water tank andthe second tank 13 is configured as a recovery water tank. Furthermore,the first tank 15 can be detachably affixed to the chassis 2 by means ofa quick fixing device and the second tank 13 can be detachably affixedto the elongated member 9 by means of a quick fixing device. The firsttank 15, i.e. the fresh water tank is connected to a piping and/orflexible tube system (not shown) so as to allow water to flow from thefirst tank 15 via a nozzle 45 (FIG. 2) to each one brush 20. The brushes20 are arranged in front of the rear wheels 3 in the front portion 16 ofthe cleaning apparatus 1 and protrude from the lower side 19 of thechassis 2 so as to be contactable with the floor 12 to be cleaned. Thebrush housing 22 can be attached to the chassis 2 at the lower side 19thereof.

The suction device 25 can comprise a front suction unit 8 arranged infront of the brushes 20, a rear suction unit 7 arranged rearward of theat least one brush 20 and a vacuum turbine 5 which is operativelyconnected to the front suction unit 8 and to the rear suction unit 7.Each of the front and rear suction units 8, 7 can be attached to thebrush housing 22. The front suction unit 8 can be configured as a linearsuction bar and can comprises a front suction channel 29 and a closingmechanism 26 which closes the front suction channel 29 when the cleaningapparatus 1 is moved in a forward travel direction. The two brushes 20,the front suction unit 8 and the rear suction unit 7 define a floorcontact region 44 for contacting the floor 12 to be cleaned when thecleaning apparatus 1 is in a working position as illustrated in FIG. 1.The closing mechanism 26 opens the front suction channel 29 when thecleaning apparatus 1 is tilted backwards so as to raise the floorcontact region 44 relative to the rear wheels 3. Apart from this theclosing mechanism 26 opens the front suction channel 29 when thecleaning apparatus 1 is moved in a backward travel direction.Furthermore, the rear suction unit 7 comprises a rear suction channel 30which is open during movement of the cleaning apparatus 1 in the forwardand the backward travel directions. By this means the suction volumeflow rate of the cleaning unit 4 can simply be increased by moving thecleaning apparatus 1 in the backward travel direction while the vacuumapplied to the rear suction unit 7 can be increased by moving thecleaning apparatus 1 in the forward travel direction in which the frontsuction unit 8 is closed. The front suction channel 29 comprises asuction opening 24 which is open towards a floor 12 to be cleaned overthe entire length of the front suction unit 8. The closing mechanism 26can be configured in such a way that it closes the suction opening 24 ofthe front suction channel 29 when the cleaning apparatus 1 is moved in aforward travel direction and opens the suction opening 24 when thecleaning apparatus 1 is moved in a backward travel direction. For thispurpose the closing mechanism 26 can comprise a lip 41 which can beconfigured as a plastic or rubber gasket, wherein the lip 41 can have afront section 27 (FIGS. 3 and 4) which frontally limits the suctionopening 24 along its entire length and a rear section 28 whichrearwardly limits the suction opening 24 along its entire length. Whenthe cleaning apparatus 1 is moved forward or backward in its workingposition with the floor contact region 44 contacting the floor 12 to becleaned the closing mechanism 26 is actuated, i.e. closed and/or openedby frictional forces acting on the front section 27 of the lip 41 due toa sliding movement of the front section 27 on the floor 12 to be cleanedwhen the cleaning apparatus is moved in its forward travel direction,i.e. with the front portion 16 of the chassis 2 ahead or in the backwardtravel direction, i.e. with the rear portion 17 of the chassis 2 ahead.

Preferably, the front section 27 and the rear section 28 of the lip 41are made of a resilient material. By this means the front section 27 ofthe lip 41 can be biased into its initial configuration where the frontsuction opening 24 is opened when the floor contact region 44 includingthe lip 41 is lifted from the floor 12 to be cleaned. The front section27 of the lip 41 has a vertical height HF protruding from the bottom ofthe brush housing 22 and the rear section 28 of the lip 41 has avertical height HR protruding from the bottom of the brush housing 22.Thereby, HF is larger than HR so that the front section 27 of the lip 41is bendable across the suction opening 24 of the front suction channel29. Upon moving the cleaning apparatus 1 in the forward travel directionthe front section 27 of the lip 41 is bent under the rear section 28 andthe suction slot 24 is closed. Upon moving the cleaning apparatus 1 inthe backward travel direction the front section 27 of the lip 41 ispushed towards the front end 38 of the cleaning apparatus 1 so that thesuction slot 24 of the front suction unit 8 is opened. Preferably, thefront section 27 of the lip 41 is bendable as far as a portion of thefront section 27 extends below the rear section 28 of the lip 41 so asto completely close the suction opening 24 of the front suction channel29. The front suction unit 8 and the rear suction unit 7 extendtransverse to the forward and backward travel direction of the cleaningapparatus 1 and—when measured orthogonal to a vertical middle plane 18of the chassis 2—the front suction unit 8 and the rear suction unit 7each have a length which is equal to or larger than a dimension of thetwo brushes 20 orthogonal to the vertical middle plane 18. Further, therear suction unit 7 comprises a rear suction channel 30 and both of thefront suction channel 29 and the rear suction channel 30 are connectedto a manifold 31 so as to be in fluid connection with a single vacuumturbine 5. The vacuum turbine 5 is configured to create sufficientvacuum for active suction of the cleaning liquid in a forward andbackward movement of the cleaning apparatus 1. The cleaning apparatus 1is configured so that in a forward movement the entire vacuumperformance is concentrated on the rear suction device 7. This due tothe fact that during a forward movement the front section 27 of the lip41 prevents any airflow at the front suction device 8. During backwardmovement the front suction unit 8 allows airflow and actively suck up ofcleaning liquid. During backward movement both suction units front 8 andback 7 actively suck up cleaning liquids.

As illustrated in FIGS. 1-3 the suction device 25 comprises a rearsuction unit 7 which is attached to the brush housing 22 by means of aresilient connecting device 10 permitting the rear suction unit 7 tomove laterally with respect to the chassis 2 against an elasticresistance provided by the resilient connecting device 10. The resilientconnecting device 10 can comprise an elongated bracket 46 having a firstend 49 affixed to the rear suction unit 7 and a second end 50 attachedto the brush housing 22 by means of an elastic connector 11. The firstend 49 of the elongated bracket 46 can be Y-shaped to provide a rigidfixation of the rear suction unit 7. The elastic connector 11 preferablyforms a pivot joint affixed to the brush housing 22 by means of afastener 47, wherein the pivot joint has an axis 42 of rotationextending vertically with respect to a forward or backward traveldirection of the cleaning apparatus 1. The elastic connector 11 canconsist of a plastic or rubber. The outer periphery of the elasticconnector 11 can be polygonally configured to prevent rotation betweenthe elastic connector 11 and the elongated bracket 46 or can berotationally stable affixed to the elongated bracket 46 by an adhesiveor any other means known to the skilled person. By means of the elasticconnector 11 the elongated bracket 46 is biased in a position of rest inwhich the elongated bracket 46 extends along a forward or backwardtravel direction of the cleaning apparatus 1. The rear suction unit 7can be rearwardly spaced apart from the brush housing 22 by a spacing ofminimum 30%, preferably minimum 35% of the diameter of one of thebrushes 20. Due to the fact that the elongated bracket 46 is elasticallyattached to the brush housing 22 the rear suction unit 7 can follow thepath of the brushes 20 when the cleaning apparatus 1 is moved along acurved path or can be elastically pressed against a vertical wall whenthe cleaning apparatus 1 is moved along this wall closely enough toelastically press the rear suction unit 7 out of its position of restagainst the elastic resistance provided by the elastic connector 11.Preferably, the rear suction unit 7 comprises a curved suction barextending on an arc around a rear portion of the two brushes 20 so thatthe brushes are partially encircled. In embodiments of the cleaningapparatus 1 with two brushes the rear suction unit 7 is preferablyconfigured as an essentially elliptically curved suction bar to fitbetter around a portion of the rear periphery of the pair of brushes 20.Further, each a stopper pin 43 can be mounted on the top side of thebrush housing 22 on either side of the vertical middle plane 18 so as tolimit the swiveling motion of the bracket 11. Preferably, the stopperpins 43 limit the swiveling motion of the bracket 11 within an angle ofmaximum ±60°, preferably of maximum ±45° and of minimum ±30°, preferablyof minimum ±35°.

As best seen in FIG. 5 the first tank 15 is attachable to the chassis 2and is configured as a receptacle with its smallest dimension Xextending vertically with respect to the forward and backward traveldirection of the cleaning apparatus 1. Further, the cleaning apparatus 1can comprise an elongated member 9 which extends from the end of thechassis 2 to the handlebar 6, wherein the second tank 13 is attachableto the elongated member 9. The second tank 13 has a smallest dimension Zextending essentially perpendicular to a plane defined by the elongatedmember 9 and the handlebar 6. One end of the elongated member 9 can berotatably affixed to the chassis 2 by means of a hinge 39 having arotational axis 40 extending in the lateral direction of the cleaningapparatus 1. By this means the elongated member 9 with the second tank13 attached thereto can be backwardly rotated about the rotational axis40 of the hinge so as to permit to clean the floor 12 under a table orunder a bench. The elongated member 9 can be adjustable and loosenablysecurable at a selected angle between −90° and +90° with respect to ahorizontal plane. Thus, the elongated member 9 with the second tank 13attached thereto can be rotated from an essentially vertical positionwhich is suitable to put aside the cleaning apparatus 1 on a minimumspace to a horizontal position permitting a reduced overall height ofthe complete cleaning apparatus 1. The brushes 20 and the rear suctionunit 7 define a floor contact region 44 when the cleaning apparatus 1 isin a working position and the first tank 15 can extend vertically withrespect to the floor contact region 44 to a level of maximum 40 cm,preferably maximum 35 cm. In a preferred embodiment each of the firstand second tanks 15, 13 can have a volume of typically 9 liters. In oneembodiment the cleaning apparatus 1 can additionally comprise amechanical actuation device (not shown), preferably a lever hoist torotate the elongated member 9 about the rotational axis 40 of the hinge39. By this means the weight of the second tank 13 must not be manuallylifted or lowered by the user during an adjustment of the elongatedmember 9 with the second tank 13 attached thereto from a verticalposition to a horizontal position or vice versa. The weight of thesecond tank 13 can be lifted or lowered by means of the mechanicalactuation device. Preferably, the first tank 15 longitudinally extendsover the front and the rear portion 16, 17 of the cleaning apparatus 1so as to have a maximum horizontal cross-sectional area. The first tank15 can taper towards the front end 38 of the chassis 2 to achieve a lowfront portion 16 of the cleaning apparatus 1 suitable to clean the floor12 under e.g. a bench.

While various descriptions of the present invention are described above,it should be understood that the various features can be used singly orin any combination thereof. The scope of the present invention isaccordingly defined as set forth in the appended claims.

1. A floor cleaning apparatus comprising: a front portion; a rearportion comprising two lateral rear wheels; a chassis; and a cleaningunit attached to the chassis; wherein the cleaning unit comprises: atleast one rotatable brush which is arranged in the front portion of thecleaning apparatus so as to be contactable with a floor to be cleaned;and a suction device including a front suction unit arranged in front ofthe at least one brush and a rear suction unit arranged rearward of theat least one brush; and wherein the front suction unit comprises a frontsuction channel and a closing member for closing the front suctionchannel.
 2. The floor cleaning apparatus according to claim 1, whereinthe closing member closes the front suction channel when the floorcleaning apparatus is moved in a forward travel direction.
 3. The floorcleaning apparatus according to claim 1, wherein the closing memberopens the front suction channel when the floor cleaning apparatus ismoved in a backward travel direction.
 4. The floor cleaning apparatusaccording to claim 1, wherein the rear suction unit comprises a rearsuction channel which remains open when the floor cleaning apparatus ismoved in a forward and when the floor cleaning apparatus is moved in abackward travel direction.
 5. The floor cleaning apparatus according toclaim 1, wherein the front suction channel comprises a suction openingwhich is open towards the floor to be cleaned over an entire length ofthe front suction unit, and wherein the closing member closes thesuction opening of the front suction channel when the floor cleaningapparatus is moved in a forward travel direction and opens the suctionopening when the floor cleaning apparatus is moved in a backward traveldirection.
 6. The floor cleaning apparatus according to claim 1, whereinthe front suction channel comprises a suction opening which is opentowards the floor to be cleaned, and wherein the closing membercomprises a lip with a front section, which frontally limits the suctionopening along its entire length, and a rear section which rearwardlylimits the suction opening along its entire length.
 7. The floorcleaning apparatus according to claim 6, wherein the closing member isactuated by frictional forces acting on the front section of the lip dueto a sliding movement of the same on the floor to be cleaned when thefloor cleaning apparatus is moved with the front portion of the floorcleaning apparatus ahead or with the rear portion of the floor cleaningapparatus ahead.
 8. The floor cleaning apparatus according to claim 6,wherein the lip is made of a resilient material.
 9. The floor cleaningapparatus according to claim 6, wherein the front section of the lip hasa vertical height HF and the rear section of the lip has a verticalheight HR, and wherein HF is larger than HR so that the front section isbendable across the suction opening.
 10. The floor cleaning apparatusaccording to claim 6, wherein the front section of the lip is bendableas far as a portion of the front section extends below the rear section.11. The floor cleaning apparatus according to claim 1, wherein the rearsuction unit comprises a rear suction channel, and wherein both of thefront suction channel and the rear suction channel are connected to amanifold so as to be in fluid connection with a single vacuum turbine.12. The floor cleaning apparatus according to claim 1, wherein the frontsuction unit and the rear suction unit extend transverse to forward andbackward travel directions of the cleaning apparatus.
 13. The floorcleaning apparatus according to claim 1, wherein when measuredorthogonal to a vertical middle plane of the cleaning apparatus thefront suction unit and the rear suction unit each have a length which isequal to or larger than a dimension of the at least one brush measuredorthogonal to the vertical middle plane.
 14. The floor cleaningapparatus according to claim 1, wherein the cleaning apparatus furthercomprises a brush housing, and wherein the rear suction unit is attachedto the brush housing by a resilient connecting device allowing the rearsuction unit to move laterally with respect to the chassis against anelastic resistance provided by the resilient connecting device.
 15. Thefloor cleaning apparatus according to claim 14, wherein the resilientconnecting device comprises an elastic connector, which forms a pivotjoint affixed to the brush housing by means of a fastener.
 16. The floorcleaning apparatus according to claim 15, wherein the pivot joint has anaxis of rotation extending essentially vertically.
 17. The floorcleaning apparatus according to claim 1, wherein the rear suction unitcomprises a curved suction bar.
 18. The floor cleaning apparatusaccording to claim 14, wherein the resilient connecting device comprisesan elongated bracket having a first end affixed to the rear suction unitand a second end attached to the brush housing by means of an elasticconnector.
 19. The floor cleaning apparatus according to claim 18,wherein the elongated bracket is biased in a position of rest by meansof the elastic connector, and wherein when in the position of rest theelongated bracket extends along a forward or backward travel directionof the floor cleaning apparatus.
 20. The floor cleaning apparatusaccording to claim 1, wherein the at least one brush is rotatable abouta rotational axis extending essentially vertically.
 21. The floorcleaning apparatus according to claim 1, wherein the floor cleaningapparatus further comprises a handlebar, which allows the floor cleaningapparatus to be moved on the floor to be cleaned.
 22. The floor cleaningapparatus according to claim 1, wherein the rear suction unit isarranged in front of the rear wheels.
 23. The floor cleaning apparatusaccording to claim 1, further comprising a first tank, which isattachable to the chassis and which is configured as a receptacle withits smallest dimension X extending vertically.
 24. The floor cleaningapparatus according to claim 23, further comprising a second tank, whichis arranged in the rear portion of the floor cleaning apparatus andwhich is configured as a receptacle having a smallest dimension Z in theforward or rearward travel direction of the floor cleaning apparatus.25. The floor cleaning apparatus according to claim 24, furthercomprising an elongated member, which extends from a rear end of thechassis, and wherein the second tank is attachable to the elongatedmember.
 26. The floor cleaning apparatus according to claim 25, whereinone end of the elongated member is rotatably affixed to the chassis bymeans of a hinge.
 27. A method of cleaning a floor using the floorcleaning apparatus according to claim 1, the method comprising the stepsof: moving the floor cleaning apparatus in a forward travel direction toclose the front suction channel so as to apply an increased vacuum inthe rear suction channel which remains open when the floor cleaningapparatus is moving in the forward travel direction; and/or moving thefloor cleaning apparatus in a backward travel direction to open thefront suction channel so as to obtain a high combined suction volumeflow through the open front suction channel and the open rear suctionchannel.